Clinicopathological characterization, FGFR alteration prevalence, and outcomes of locally advanced or metastatic urothelial cancer in Latin America (LACOG 1518)

e16549

Background: Treatment of Urothelial Cancer (UC) is rapidly evolving with innovative biomarker-based approaches. Alterations in the gene encoding fibroblast growth factor receptor (FGFR) are frequent in UC and are an emerging focus for targeted therapy. However, real-world data on FGFR prevalence, as well as clinicopathological characteristics and outcomes of patients (pts) with advanced UC in Latin America is lacking. Methods: LACOG 1518 is a multicenter multinational study that retrospectively included pts diagnosed with metastatic or relapsed UC between Jan-2016 and Dec-2019. Clinicopathological characteristics, outcomes and treatment patterns were retrieved from medical records. Archival tumor samples were analyzed for FGFR alterations by NGS. Results: Two hundred thirteen pts were included across 24 centers in 4 Latin American countries. Median age was 68 years (range, 31-90), most pts (75%) had PS 0-1, and 83 (39%) pts had clinical stage IV at diagnosis. Bladder was the primary site of disease in 190 (89%) pts, 92 (43.2%) pts had histological variants of UC - 46 (21.6%) pts with adenocarcinoma differentiation and 16 (7.5%) with squamous-cell differentiation. Patients with relapsed locoregional disease not candidates for curative therapy comprised 10.3% of the sample. Among pts with metastatic disease, visceral metastases were present in 99 (51%) pts. FGFR alterations eligible for treatment with FGFR inhibitors (FGFRi) were identified in 29 (14.8%) out of 196 pts tested and included 29 mutations (14 S249C, 7 Y373C, 5 R248C and 3 G370C) and 13 fusions (8 FGFR3-TACC3, 2 FGFR3-BAIAP2L1, 2 FGFR2-BICC1 and 1 FGFR2-CASP7). Other FGFR alterations were also present in 6 (3.1%) pts. Median overall survival since initial diagnosis and advanced disease were 31.6 months (95% CI, 25.5 – 37.6) and 15.2 months (95% CI, 12.4 – 17.9), respectively. Median time to treatment failure to the first treatment line was 3.9 months (95% CI, 3.0 – 4.4). Regarding treatment patterns, 175 (82.1%) pts received first line treatment: 127 (72.6%) combined chemotherapy, 29 (16.6%) immunotherapy alone, 15 (8.6%) single agent chemotherapy, and 4 (2.3%) chemo-immunotherapy. Gemcitabine-platinum combinations were the backbone of choice in 93.7% of pts receiving combined chemotherapy. Pembrolizumab and atezolizumab were the chosen first-line agents for 10.3% and 4% of the treated pts, respectively. Considering all treatment lines, 75 (35.2%) and 3 (1.4%) pts were exposed to immunotherapy and FGFRi in the course of their disease, respectively. Conclusions: The prevalence of FGFR alterations in advanced UC in Latin America is similar to those described in other regions. Our data suggest limited access to FGFR inhibitors for the treatment of advanced UC in Latin America.

Survival analysis of the randomized phase II trial to investigate androgen signaling inhibitors with or without androgen deprivation therapy (ADT) for castration-sensitive prostate cancer: LACOG 0415

5076

Background: LACOG 0415 is a phase II, open-label, clinical trial evaluating ADT-free alternatives for advanced castration sensitive prostate cancer (CSPC). Methods: Patients with locally advanced, high-risk biochemical recurrence or metastatic CSPC were randomized (1:1:1) to receive ADT with abiraterone acetate plus prednisone (ADT+AAP), apalutamide alone (APA), or apalutamide with AAP (APA+AAP). The primary endpoint of the trial was the proportion of patients who achieved PSA≤0.2 ng/mL level at week 25. Patients without disease-progression and with clinical benefit after week 25 were allowed to maintain treatment at the discretion of physicians. Herein, we presented the outcomes of 2 year-overall survival (2y-OS) and time-to-treatment failure (TTF). The time-to-event endpoint was estimated by Kaplan-Meier method and compared by stratified log-rank test. Results: 128 patients were randomized to the ADT+AAP (n = 42), APA (n = 42), and APA+AAP (n = 44) arms. At week 25, PSA≤0.2 ng/mL was observed in 75.6% (95%CI 59.7%-87.6%), 60.0% (95%CI 43.3%-75.1%), and 79.5% (95%CI 63.5%-90.7%) of patients in the ADT+AAP, APA, and APA+AAP arms, respectively. 110 patients continued treatment after week 25. At the 2-year visit, 80 (62.5%) patients remained on the study medication. Median TTF was 24.0 months (95%CI 23.3 - 24.0) with ADT+AAP, 24.0 months (95%CI not estimated) with APA, and 24.0 months (95%CI 13.0-24.0) with APA+AAP. The main reasons for treatment discontinuation were disease progression (n = 8, 6.3%), toxicity (n = 10, 7.8%), death (n = 6, 4.7%), withdrawal (n = 4, 3.1%), and other (n = 19, 14.8%). The estimated proportion of patients who were alive at 2 years (2y-OS rate) was 92.5% (95%CI 84.3-100) with ADT+AAP, 87.9% (95%CI 77.9-97.8) with APA, and 92.7% (95%CI 84.8-100) with APA+AAP (p = 0.5926). 2y-OS was 92.9% (95% CI 85.3 - 96.2) in patients with PSA ≤ 0.2 ng/mL at week 25, while 2y-OS was 85.0% (95% CI 72.9-97.1) in patients with PSA > 0.2 ng/mL at week 25 (p = 0.1250). Conclusions: Patients with advanced CSPC treated with ADT+AAP, APA, or APA+AAP had high rates of PSA response and favorable 2y-OS. PSA ≤ 0.2 ng/mL at week 25 seems to be a surrogate prognostic predictor of OS in advanced CSPC. In the overall sample, patients with PSA ≤ 0.2 ng/mL at week 25 had higher 2y-OS rate than those with PSA > 0.2 ng/mL at week 25 (92.9% vs. 85.0%), however without statistical significance. Clinical trial information: NCT02867020.

A phase 2 randomized clinical trial of abiraterone plus ADT, apalutamide, or abiraterone and apalutamide in patients with advanced prostate cancer with non-castrate testosterone levels (LACOG 0415)

BACKGROUND

Androgen deprivation therapy (ADT) combined with apalutamide, abiraterone acetate plus prednisone, enzalutamide, or docetaxel are the standard treatments for advanced castration-sensitive prostate cancer (CSPC). We investigated ADT-free alternatives for advanced CSPC.

PATIENTS AND METHODS

LACOG 0415 is a phase 2, open-label, non-comparative, randomized trial. Patients with advanced CSPC were randomized (1:1:1) to receive goserelin plus abiraterone acetate and prednisone (ADT plus AAP arm), apalutamide (APA arm), or apalutamide plus abiraterone acetate and prednisone (APA plus AAP arm). The primary endpoint was the proportion of patients with PSA of ≤0.2 ng/mL at week 25 in the modified intention-to-treat population. Safety analyses were performed in all patients with at least one dose of the study drug.

RESULTS

Of 128 randomized patients, 120 patients were evaluable for PSA response at week 25; 17.2% had a high-risk biochemical recurrence, 8.6% had locally advanced disease, and 74.2% had distant metastases. At week 25, PSA of ≤0.2 ng/mL was observed in 75.6% (95%CI 59.7%-87.6%), 60.0% (95%CI 43.3%-75.1%), and 79.5% (95%CI 63.5%-90.7%) of patients in ADT plus AAP, APA, and APA plus AAP arms, respectively. PSA decline of ≥80% was observed in 100%, 90.0%, and 97.4%, respectively. Grade 3-4 AEs were observed in 31.0%, 21.4% and 36.4%, respectively. Testosterone levels increased significantly in the APA arm and decreased significantly in ADT plus AAP and APA plus AAP arms.

CONCLUSIONS

ADT-free alternatives provide a high PSA response in advanced CSPC, although the APA arm did not reach the expected rate of PSA of ≤0.2 ng/mL at week 25. These results warrant further investigation of ADT-free treatments as alternatives in advanced CSPC.

SOURCE STUDY REGISTRATION

ClinicalTrials.govNCT02867020.

Clinical-pathological characterization and outcomes of metastatic urothelial cancer in Latin America: Retrospective and translational multicenter database (LACOG 1518)

TPS497

Background: There is lack of high-quality and comprehensive data on advanced urothelial cancer in Latin America. Pathological and clinical outcomes information of this cancer can help the scientific community to understand the current standard of treatment and identify possible gaps for optimal care. Very few translational studies were performed in advanced urothelial cancer in developing countries describing the prevalence of key biomarkers for targeted agents and immunotherapy. Methods: LACOG 1518 is a large multi-institutional retrospective study that will collect information about sociodemographic data, treatment and outcome of patients diagnosed with recurrent/ metastatic urothelial cancer in Latin America between January 2016 and December 2019. Socio-demographic characteristics, clinical-pathological features, treatment patterns and outcomes will be extracted from medical charts. Tumor tissue will be collected for fibroblast growth factor receptor (FGFR) gene mutation or fusion test in a central laboratory. A biorepository will be built for future translational research including PD-L1 test and next generation sequencing. Primary endpoint consists on characterize demographic, socioeconomic factors, medical and oncological history of patients diagnosed with recurrent/metastatic urothelial cancer. This study aim to describe treatment sequence, duration, best response and progression time in each line of therapy as well as survival at 1 and 2 years. Translational research endpoints are biomarkers prevalence and association with treatment responses and outcomes.

Abiraterone acetate in patients with metastatic castration-resistant prostate cancer, chemo-naive, who received a prior diethylstilbestrol therapy

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Background: The use of diethylstilbestrol (DES) for the treatment of metastatic castration resistant prostate cancer (mCRPC) is very common in developing countries. Retrospective data suggests that abiraterone acetate (AA) is active in patients that progressed to DES. This phase II study evaluated the efficacy and safety of abiraterone acetate in chemotherapy-naïve patients with metastatic CRPC who have progressed to DES. Methods: Patients with DES−refractory metastatic CRPC with ongoing ADT, serum testosterone level < 50 ng/dL and ECOG of 0-2 were included. All patients received AA 1,000 mg with prednisone 5 mg once daily in a 28 days cycles. The primary endpoint was the time to PSA progression (PSAP) by PCWG2 and was previously reported. We present here secondary endpoints: overall survival, PSA response, maximum PSA change from baseline and safety. Results: A total of 46 patients were enrolled, median age was 69.8 years, 76% had gleason > = 7 at diagnosis, median time from metastatic disease to DES discontinuation was 25.9 months, and a median duration of prior DES of 7.2 months. AA treatment resulted in median time to PSA progression of 7.3 months. PSA response rate (³ 50%) was 47.5% (95% CI: 36,1% to 68,5%) at 12 weeks and 57.5% (95% CI: 27.0% to 59.1%) at any time. 93.4% received chemotherapy after progression to AA. The median overall survival was 29.6 months. Substantial declines in serum androgens from baseline to week 12 occurred and in this group a higher proportion of PSA responses occurred. The incidence of adverse events (AEs) related to AA was 74% and prednisone 59%. Hypertension (21.7%), fatigue (19.6%) and oedema peripheral (13.0%) were the most frequent AA related AEs. The most frequent prednisone related AEs were hyperglycaemia (15.2%) hypertension (10.9%). Serious AEs occurred in 23.9% of subjects and 3 subjects (6.5%) died of AEs not related to study drugs. Conclusions: AA is well tolerated and demonstrated activity in mCRPC patients previously treated with DES, therefore it should be considered an option in chemo-naïve patients. Serum androgens levels tend to decrease with AA treatment and are associated with PSA responses. Clinical trial information: NCT02217566.

Health-related quality-of-life (HRQoL) analysis from a randomized phase II trial of androgen signaling inhibitors with or without androgen deprivation therapy (ADT) for castration-sensitive prostate cancer: LACOG 0415

64

Background: LACOG0415 is a 3-arm randomized trial evaluating ADT with abiraterone acetate plus prednisone (ADT+AAP), apalutamide alone (APA) or apalutamide with AAP (APA+AAP) for patients with locally-advanced, high-risk biochemical recurrence or metastatic castration-sensitive prostate cancer (ASCO 2020). In this trial, ADT+AAP and APA+AAP achieved the primary endpoint of percentage of patients with PSA ≤ 0.2 ng/mL at week 25. Apalutamide alone showed a high PSA decline > 50% rate, but did not achieve the pre-specified PSA threshold. Here we report patient-reported outcome data using Functional Assessment of Cancer Therapy-Prostate (FACT-P). Methods: HRQoL was measured in the overall population using the FACT-P questionnaire, comprising 5 subscales: physical wellbeing (PWB), functional wellbeing (FWB), emotional wellbeing (EWB), social/family wellbeing (SFWB), and prostate cancer subscale (PCS). Scores for each patient were measured at baseline and every four weeks until week 25. Questionnaire completion was defined as ≥ 1 question answered at an assessment time point. Analysis of HRQoL change from baseline and deterioration included only patients with baseline and ≥ 1 postbaseline score. Differences greater than 10-points in FACT-P total score and differences greater than 3-points in PWB, FWB, EWB, SFWB, and PCS scores were considered clinically significant. The time-to-event endpoint was estimated by Kaplan-Meier method and compared by stratified log-rank test. Results: 128 patients were included in LACOG0415 trial and 122 of them completed the HRQoL assessments (ranging from 95.3% at baseline to 79.7% at week 25). FACT-P and all subscales scores were similar for all three arms at baseline. There were no meaningful differences in FACT-P scores at baseline and at week 25 between the 3 arms. The subscales scores also showed no statistically differences at baseline and at week 25. Time to FACT-P deterioration did not show any statistically difference between three arms ( P=0.3371). Conclusions: ADT free alternatives with APA alone or APA+AAP did not show meaningful differences in HRQoL in patients with advanced castration-sensitive prostate cancer compared to ADT+AAP. The short follow-up period limited the ability to explore differences in HRQoL after 25 weeks. Larger studies with longer follow-up are needed to further evaluate HRQoL with ADT-free strategies. Clinical trial information: NCT02867020. [Table: see text]

Phase II randomized study of abiraterone acetate plus prednisone (AAP) added to ADT versus apalutamide alone (APA) versus AAP+APA in patients with advanced prostate cancer with noncastrate testosterone levels: (LACOG 0415)

5505

Background: ADT combined with AAP, APA, enzalutamide or docetaxel are among the standard treatment options to patients (pts) with hormone sensitive advanced/metastatic prostate cancer (PC). However, treatment-related adverse events (TRAEs) due to ADT impact negatively on the quality of life of these patients. Effective options with fewer TRAEs are required. Methods: LACOG 0415 is a phase II, randomized trial (1:1:1) evaluating the use of AA 1000mg po + prednisone 5mg po BID + ADT versus APA 240mg po alone versus AA 1000mg po + prednisone 5mg po BID + APA 240mg po in patients with advanced PC with non-castrate testosterone levels and indication of ADT (N+ or M+ or biochemical relapse combined with PSA ≥ 20 ng/ml or with PSA≥4 ng/ml and PSA doubling-time < 10 months). Stratification factors: metastatic disease (+/-). Primary endpoint was the percentage of pts who achieved PSA ≤ 0.2 ng/mL at Week 25, we estimated a PSA response rate of 65% in each of the three arms with a null hypothesis of 45%, power of 80% and alfa 5%, using Fleming one-stage method. Secondary endpoints were percentage of pts with ≥ 80% and ≥ 50% decline in PSA at week 25, radiographic progression-free survival (rPFS) and safety. Results: 128 patients were randomized between Oct 2017 and Apr 2019, and 122 pts were evaluable for PSA response. Median age was 69y (range, 53-88); most pts had ECOG PS0-1(99%). 17% of pts had biochemical relapse only, 9% N+ and 74% M+ disease. At week 25 the PSA was ≤ 0.2 ng/mL in 76% of pts in AAP+ADT arm, 59% in APA, and 80% in APA+AAP. All pts had a decline of ≥ 50% in PSA at week 25. 97% had a decline of ≥ 80% in PSA at week 25: 100% of pts in AAP+ADT arm, 95% in APA and 98% in APA+AAP. A total of 3 pts had clinical progressive disease, one in each arm. Two of them also had radiological progression at week 25, 1 pt in AAP+ADT arm and 1 pt in APA. TRAEs rates of any grade were 71% in AAP+ADT arm, 64% in APA, and 65% in APA+AAP. TRAEs rates of Grade≥3 were 12% in AAP+ADT arm, 9% in APA and 16% in APA+AAP. 9 pts (7%) discontinued the treatment before the week 25, 5(4%) of them due to toxicity: 1 pt from AAP+ADT, 2 pts from APA, and 6 pts from APA+AAP. Conclusions: The AAP+ADT and APA+AAP groups showed high effectiveness in terms of PSA response. Radiologic disease control and the decline of ≥ 80% in PSA at week 25 were similar among all treatment arms. APA alone had less toxicity. APA+AAP and APA alone are promising regimens in this setting. No new safety signal was detected in the study. Clinical trial information: NCT02867020 .

Abiraterone acetate plus prednisone (AAP) in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer (mCRPC) and prior diethylstilbestrol (DES) therapy: Preliminary results

235

Background: AAP is approved for patients with chemotherapy-naïve mCRPC, but the population with previous use of DES was not studied before. DES is a commonly used hormone therapy for mCRPC in second and plus lines, especially in developing countries, due to lack of access to novel and efficacious therapies. The objective of this trial is to describe the efficacy and safety of AAP after DES treatment in patients who are chemotherapy-naïve, potentially affecting chemotherapy onset. This is the first and only prospective trial to show this data. Methods: This phase 2 multicenter, open-label single-arm study evaluated 46 patients receiving AA (1000 mg daily) + low-dose prednisone (P; 10 mg daily) and androgen deprivation therapy in patients with DES–refractory mCRPC enrolled from Oct 2014 to Oct 2015. The primary efficacy endpoint was time to prostate-specific antigen progression (PSAP) by Prostate Cancer Working Group (PCWG2) criteria. Secondary endpoints included PSA response (≥50% reduction), overall survival, and safety. Results: At baseline, median age was 69 years, median PSA was 40 ng/mL, there were no visceral metastases, 98% of patients had Eastern Cooperative Oncology Group Performance Status 0-1, and 44% had Gleason scores ≥7. Thirty two subjects (71.1%) had PSAP. PSA response was achieved by 47% of patients at week 12 and 56% at any time. Three patients remain on study drug and 4 are in follow-up. AA treatment continued until PSAP, clinical progression, consent withdrawal, or unacceptable toxicity. The median duration of study treatment was 8.6 months. The median time to PSAP was 7.4 months (95% CI = 5.6-9.4) and the median overall survival was 25.6 months (95% CI = 15.7-NE). Treatment-related adverse events included hypertension (19.6%), hyperglycemia (19.6%), fatigue (17.4%), and hypokalemia (4.5%); most grade 1-2. Conclusions: The present study confirmed that AAP provides PSA responses even in heavily treated patients, showing clinical benefit post-DES in chemotherapy-naive mCRPC patients. It also confirmed tolerability of AAP, with an easily manageable toxicity profile. Clinical trial information: NCT02217566.

Abstract OT1-1-08: Clinical outcomes among ErbB2+ MBC patients treated with lapatinib-capecitabine after trastuzumab progression: Role of early switch to lapatinib (TYCO study)

Background: Lapatinib in combination with capecitabine is a standard of care treatment for ErbB2+ metastatic breast cancer (MBC) patients who have progressed after anthracyclines, taxanes and trastuzumab treatment. Results from the lapatinib pivotal trial showed that the addition of lapatinib to capecitabine increased median time to progression (TTP) even among heavily pre-treated patients (median of 4 prior lines of therapy). A post-hoc exploratory sub-group analysis of this trial suggested that earlier administration of lapatinib-capecitabine in MBC patients who progress after trastuzumab may produce better clinical outcomes. The TYCO study was designed to evaluate if early initiation of lapatinib-capecitabine in patients with ErbB2+ MBC who have progressed on trastuzumab-containing regimen improves TTP in comparison with a delayed start of the therapy.

Trial design: TYCO is an international, multicenter, prospective, observational study in 269 ErbB2+ MBC patients whose disease has progressed after treatment with trastuzumab in the metastatic setting. Two cohorts will be compared; Group 1: patients receiving lapatinib-capecitabine just after the first trastuzumab progression, and Group 2: patients receiving lapatinib-capecitabine after two or more lines of treatment after first trastuzumab progression. The study duration is of 12 months with data collection at baseline and approximately every 3 months thereafter.

Major Eligibility Criteria: 1. Females ≥18y with confirmed ErbB2+ MBC who have progressed after a previous trastuzumab-containing regimen,2. Pts eligible for standard therapy with lapatinib-capecitabine at approved conventional doses, as per local approved label.3. Pts eligible to start standard treatment with Lapatinib-capecitabine at conventional doses, or receiving standard treatment with Lapatinib-capecitabine at conventional doses, for no longer than 10 weeks from the start of the treatment to the date of inclusion in the study;

Aims: Primary objective of this study is to determine if early switch to lapatinib-capecitabine in patients with ErbB2+ metastatic breast cancer who have progressed on trastuzumab containing regimen improves time to disease progression as determined by treating physician either clinically or radiologically. Secondary objectives include overall response rate and overall survival.

Statistical Methods: Kaplan-Meier plots will be used to describe the median TTP after start of lapatinib-capecetabine. Cox proportional hazard model will be developed to estimate the adjusted hazard ratio (and 95% confidence intervals) comparing TTP for the two treatment group using propensity score methods (trimmed sample, adjustment for the continuous propensity score measure, and doubly robust adjustment) to adjust for potential confounding by indication that may arise due to the non-randomised design.

Present and Target Accrual: Enrollment began in February 2010, and as per May 2012, 266 patients have been included from Turkey, Venezuela, Argentina, Saudi Arabia and Colombia.